Executive Summary

CVE-2025-11941 is a vulnerability in e107 CMS versions up to 2.3.3, specifically in the Avatar Handler component of the Media Manager. It allows an authenticated admin user to perform arbitrary file deletion on the server by exploiting improper validation of the 'multiaction[]' parameter in the file /e107_admin/image.php. The application attempts to filter out directory traversal sequences like '../', but this filter can be bypassed using patterns like '..././', enabling deletion of files outside the intended directory. This can be done remotely by manipulating POST requests to the avatar deletion endpoint. [1, 2, 3]

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Impact Analysis

This vulnerability can lead to arbitrary deletion of files on the server by an authenticated admin user, potentially causing data loss, denial of service, or further exploitation of the system. Since files outside the intended media directory can be deleted, critical system or application files might be removed, disrupting service availability and integrity. [1, 2, 3]

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Detection Guidance

This vulnerability can be detected by monitoring HTTP POST requests to the endpoint `/e107_admin/image.php?mode=main&action=avatar` that include the `multiaction[]` parameter with suspicious path traversal patterns such as `..././`. You can use network traffic inspection tools or web server logs to identify such requests. For example, using grep on web server logs: `grep 'e107_admin/image.php?mode=main&action=avatar' /var/log/apache2/access.log | grep multiaction`. Additionally, intercepting and inspecting POST requests with tools like Burp Suite or curl can help detect exploitation attempts. Checking for unexpected file deletions in the server file system, especially in directories outside the intended media folder, can also indicate exploitation. [1, 2]

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Mitigation Strategies

Immediate mitigation steps include restricting access to the admin backend to trusted users only, monitoring and blocking suspicious POST requests containing path traversal patterns in the `multiaction[]` parameter, and applying strict input validation and canonicalization on file paths to prevent directory traversal. If possible, restrict file deletion operations to a whitelist of allowed files or directories and confine file operations strictly to a controlled media-only directory. Since no official patch or vendor response is available, consider replacing or upgrading the affected product to a secure alternative. Additionally, monitor server logs for signs of exploitation and maintain regular backups to recover from potential data loss. [1, 3, 2]

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